This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. F-box proteins are tumor suppressor genes that are part of the ubiquitin ligase complex known to mediate protein-protein interactions via their 50 amino acid F-box domain. We hope to identify F-box substrates (proto-oncogenes) by observing the changes of proteins over time between the F-box deletion strains in Saccharomyces cerevisiae versus the wild-type control using stable isotope labeling (D3-Leucine).